1. Technical Field
The present invention relates generally to a rotary electronic device such as a rotary encoder which includes a push/turn operating button designed to be locked in a push-in position by finger pressure of an operator and returned to an unlocked position by depressing it again.
2. Background of Related Art
Modern electronic equipment is becoming small in area of a front control panel for reduction in size thereof and increasing in number of electronic parts for advancement of the electronic equipment. This gives rise to a problem in that an interval between adjacent two of operating buttons of electronic devices is shortened so that when an operator moves the operating button of one of the devices, a fingertip of the operator may interfere with another of the devices.
In order to avoid the above problem, an improved electronic device may be used which is designed to lock in push-in positions some of operating buttons not required to be moved, while maintaining the others in projecting positions for ease of manual operations.
FIGS. 16 to 19 show a conventional rotary encoder as one example of the above described electronic device.
The rotary encoder includes generally an encoding mechanism 1 shown on the right side of the line A--A and a locking mechanism 2 shown on the left side of the line A--A.
The encoding mechanism 1 includes, as shown in FIG. 17(a), an operating shaft 3 and a resinous rotor 5. The operating shaft 3 is retained by a bearing 4 so as to be rotatable and movable in an axial direction. The rotor 5 engages a semicircular portion 3A of the operating shaft 3 so that it is rotatable along with rotation of the operating shaft 3, but restricted from moving in the axial direction of the operating shaft 3.
On a rear surface of the rotor 5, a rotary contact plate 6, as shown in FIG. 19, consisting of a central ring portion 6A and radially extending fins 6B is provided in insert molding. Three resilient contacts 8A, 8B, and 8C which extend from an insulating substrate 7 disposed at a given interval away from the rotary contact plate 6, elastically engage the central ring portion 6A and one of the radially extending fins 6B.
The encoding mechanism 1 is enclosed with a metallic cover 9. The cover 9 has, as shown in FIG. 16, claws 9A bent to connect the encoding mechanism 1 with the locking mechanism 2 together with the insulating substrate 7.
FIG. 17(a) shows an unlocked position of the operating shaft 3. The rotation of the operating shaft 3 causes the rotor 5 to be rotated so that the resilient contacts 8A to 8C slide on the central ring portion 6A and the radially extending fins 6B to produce pulse signals between terminals D and E and between terminals D and F connected to the contacts 8A to 8C.
The locking mechanism 2 has substantially the same structure as that taught in Japanese Patent Second Publication No. 60-52563. Specifically, the locking mechanism 2 includes a locking member 11 disposed within a box-like cover 10 which is moved by the axial movement of the operating shaft 3 against a spring force of a coil spring 12. The operating shaft 3 , as shown in FIG. 18, engages at a groove 3B an opening 11A of the locking member 12.
A hook 15 is installed in a bottom plate 13 of the cover 10. The hook 15 has a pin 14 which is urged inward of the cover 10 by a plate spring 16 at all times and which selectively establishes engagement and disengagement with and from a heart-shaped groove 11B formed in the locking member 11 according to the axial movement of the locking member 11 in a locked position and an unlocked position as shown in FIGS. 17(a) and 17(b).
The rotary encoder is usually installed in electronic equipment, as shown in FIG. 16, by soldering a mounting leg 10A extending from a rear end portion of the cover 10 and terminals 8D to 8F extending from the insulating substrate 7 to a printed-circuit board 18 extending perpendicular to a front control panel 17 or parallel to the operating shaft 3. However, in modern reduced-size electronic equipment, electronic parts are required to be small in size and installed on a printed-circuit board disposed parallel to the front control panel 17 or perpendicular to the operating shaft 3. The above conventional rotary encoder has the locking mechanism 2 disposed behind the encoder mechanism 1 and thus does not meet such requirements.